The invention relates to a radio system, more particularly to a method of scheduling air interface capacity between different user services.
One of the major problems in mobile telephone systems is limited radio capacity. In current systems, a certain amount of radio capacity is reserved for each user having a circuit switched connection for the entire duration of a connection. In packet switched transmission, where the data transferred is typically generated in bursts, it is a waste of radio capacity to keep radio capacity reserved according to the highest momentarily needed transmission capacity. Different kinds of methods have therefore been developed for flexible allocation of radio capacity.
A new problem is that a single user may use simultaneously several different services. A certain amount of total capacity to be used for data transmission is then reserved for the user. The user also wants to use the capacity he is paying for as efficiently as possible.
Several such services exist simultaneously and the system has to be efficient in supporting diverse combinations of services. In third generation mobile telephone systems, a wide variety of services and service combinations are available. As these services have variable rates and the maximum instantaneous bit rate of each service may occur rarely, it is not efficient to allocate capacity based on the worst service bit rate combination, i.e. every service transmitting at the highest possible bit rate. On the other hand, a sudden need for more capacity may arise for some service, in which case the system should be able to borrow extra capacity very quickly. As a system option, a user equipment (UE) having multiple bearer services can be managed as one single radio link connection, where radio capacity is allocated for the whole link. Internally, UE has the task of managing the scheduling of multiple bearer transmission. This should reduce the resource management task in the network and it also reduces scheduling delay as it is now carried out internally by the UE. However, if multiple bearer services have different QoS (Quality of Service), e.g. different level of error protection by channel coding, this leads to a problem that the radio resource used to transmit one information bit of one bearer does not equal to the resource used to transmit one information bit of another bearer.
An object of the invention is therefore to provide a method and an equipment implementing the method in such a way that the above problems can be solved. This is achieved with the method described below, which is a method of scheduling air interface capacity between user services in a radio system, comprising: defining a nominal service bit rate as a bit rate before channel coding and service specific rate matching; defining a nominal capacity of the service as a bit rate after channel coding and service specific rate matching; defining an effective coding rate of the service by dividing the nominal service bit rate by the nominal capacity of the service. The method also comprises scheduling air interface frame capacity between at least two different services: computing the bit rate of the first service by multiplying the nominal capacity of the first service by the effective coding rate of the first service, and adding to this normal bit rate of the first service the borrowed extra capacity of at least one other service, and the bit rate obtained from the extra capacity is computed by multiplying a predetermined amount of the nominal capacity of the other service by the effective coding rate of the first service.
The invention also relates to an other method of scheduling air interface capacity between user services in a radio system, comprising: defining a nominal service bit rate as a bit rate before channel coding; defining a nominal capacity of the service as a bit rate after channel coding; defining an effective coding rate of the service by dividing the nominal service bit rate by the nominal capacity of the service. The other method also comprises scheduling air interface frame capacity between at least two different services: computing the bit rate of the first service by multiplying the nominal capacity of the first service by the effective coding rate of the first service, and adding to this normal bit rate of the first service the borrowed extra capacity of at least one other service, and the bit rate obtained from the extra capacity is computed by multiplying a predetermined amount of the nominal capacity of the other service by the effective coding rate of the first service.
The invention also relates to a radio transmitter for transmitting information of at least two different user services, comprising: a channel coder in each service information branch for coding the information; a rate matcher connected to the output of the channel coder in each service information branch for performing service specific rate matching for the information; means for defining a nominal service bit rate as a bit rate before channel coding and service specific rate matching, means for defining a nominal capacity for the service as a bit rate after channel coding and service specific rate matching; means for defining an effective coding rate for the service by dividing the nominal service bit rate by the nominal capacity of the service. The radio transmitter also comprises means for scheduling air interface frame capacity between at least two different services, including: means for computing the bit rate of the first service by multiplying the nominal capacity of the first service by the effective coding rate of the first service, and means for adding to this normal bit rate of the first service the borrowed extra capacity of at least one other service, and the bit rate obtained from the extra capacity is computed by multiplying a predetermined amount of the nominal capacity of the other service by the effective coding rate of the first service.
The invention also relates to an other radio transmitter for transmitting information of at least two different user services, comprising: a channel coder in each service information branch for coding the information; means for defining a nominal service bit rate as a bit rate before channel coding; means for defining a nominal capacity for the service as a bit rate after channel coding; means for defining an effective coding rate for the service by dividing the nominal service bit rate by the nominal capacity of the service. The other radio transmitter also comprises means for scheduling air interface frame capacity between at least two different services, including: means for computing the bit rate of the first service by multiplying the nominal capacity of the first service by the effective coding rate of the first service, and means for adding to this normal bit rate of the first service the borrowed extra capacity of at least one other service, and the bit rate obtained from the extra capacity is computed by multiplying a predetermined amount of the nominal capacity of the other service by the effective coding rate of the first service.
The invention is based on the presentation of a simple and fast reallocation algorithm, wherein the usable bit rate for the service bits is calculated using the nominal capacity of the service, the coding rate, and the borrowed capacity of at least one other service.
The method and system of the invention provide several advantages. Flexibility of the system is improved so that the aggregate capacity allocated for the user services can be easily scheduled dynamically between services according to the need and the service priority, even for each air interface frame separately. The radio capacity of the system will therefore be more fully utilized.